Orangutans
By David

Did you know that orangutans are the largest tree-dwelling animals? They live in only two places in the world in southeast Asia.  Orangutans are disappearing from the world because people are cutting down the trees in the tropical rainforests where they live.  Ten years ago there were about 40,000 orangutans alive in the wild.  Today there are only 20,000!

Orangutans have no spoken language. Ape vocal chords can’t make words like people, but they can learn sign language.

The orangutan can make 13 to 15 different types of vocalizations.  They have the same senses as humans do, including hearing. Male orangs have a sac hanging from their throat that helps them make loud sounds. The orangutans use this sac to make a call known as a long call;  it is made up of different calls after a bellow.  It is used to call females, claim their territory, and to keep out other males.  The loud call is important because it is hard for orangs to see other orangs since they spend their time in trees.

Orangs use facial expressions to show their emotions.  They also use body language.  When an orangutan feels threatened he grunts, breaks branches, and shakes trees. Monkeys have many more warning calls and vocalizations than orangs because unlike monkeys, orangs spend a lot of time alone and have few predators.          

Orangs remove dead skin and parasites from one another.  This will strengthen social bonds.  This occurs between a mother and her offspring.

Visual communication is the most important kind of communication for orangutans. They use a lot of different behaviors to communicate. Within small groups, orangs communicate with lip smacking. They scream when they’re scared, and males grind their teeth when frustrated.  Usually when orangs are smiling, they are showing fear or aggression.  When an orangutan is in pain, it closes its eyes and puts its arms behind its head.  Orangs use different behaviors when they are feeling anti-social.  Like waving their arms and throwing sticks.  Orangs yawn like people, but they don’t do it when they’re tired; instead, they do it when they are embarrassed or frustrated.  Baby orangs show that they want food by holding their hand out.  They cup their hand under their mom’s chin.  Orangs use their eyes to communicate, but don’t seem to use staring to communicate (chimps and gorillas do).  Young orangs beg for food by looking back and forth between their mom’s eyes and the piece of food.   

Some projects have been done to teach orangs how to use sign language.  They seem to learn new signs even a little bit faster than chimpanzees.  They are also able to use different signs together in new ways.  

An adult male orang weighs 150 to 200 lbs.  Adult females weigh  about one half as much as a male does.  The orangs face, ears, palms, and soles of their feet are hairless.  Orangs have bluish-black skin covered by reddish- brown hair.

Orangutans have a good sense of hearing and excellent color vision.  Orangs are 2/3 the size of gorillas.  The orang has a large head with a prominent face area.  An adult male has large cheek flaps that get larger as the orangutan gets older.

Orangs have sharp teeth in front for tearing food and molars in in the back for chewing.

Orangs have white around their irises like people (most animals do not).  The orangs eyes, hands, teeth, ears, and feet are similar to people.

A male orangutan is four times stronger than a man is.

There are two subspecies of orangutan.  One lives in Borneo, and the other lives in Sumatra. Borneo and Sumatra are tropical islands  Orangutans are hard to study because they are almost always hidden in trees in the dense rain forest. Orangs are arboreal, which means that they live mostly in trees. They live only in forests, including primary rainforests, swamp forests and montane forests. 

80% of orangutan habitat has been lost due to logging and farming. This is the biggest danger that orangs face. Loss of habitat is the reason why they are an endangered species.

Most males claim a territory of about two miles. Once male orangs grow very large, they spend more time on the ground because they are too heavy to hang in the trees. Otherwise orangutans seldom come down from the trees.

Orangs are omnivores but are mostly herbivores (animals that only eat plants). Omnivore means that they eat both plants and animals.  Sometimes orangutans are described as frugivores, which means that they really like to eat fruit. They eat figs, plums, lichees, wadans, mangos, rambutans, and durians which can weigh 30 lbs.  

Orangs eat many other foods. They eat leaves, seeds, tree bark, plant bulbs, tender plant shoots, and flowers. Sometimes they eat insects, birds and small mammals.  Their favorite insects to eat are termites and ants.  The orang puts a stick in a termite nest, and then lets the termites run up the stick.  Then they eat the termites. They drink water collected between tree branches.  

The mother raises her baby by herself.  The baby nurses for about four years.  They have a baby every 7-9 years.  Almost one half of all babies die in the wild.  At birth, babies weigh 2.5 to 3.5 lbs.  

A female orang hangs from a tree branch and shows her pernuem to the male to solicit a mating from the male. The males often fight each other over the female.  

• Orangutan is pronounced O-rang-u-tan.
• Did you know that orangutans from Sumatra are brighter in color than the ones from Borneo?  
• The orang has 4 hands because its toes are just as nimble as its fingers.
• Orangutan actually means “person of the forest.”
• 19,000 to 25,000 orangutans live in the wild.
• 96.7% of orangs genes are the same as humans genes. 
• Orangs are the largest tree- dwelling animal in the world.
• Orangs have only a few predators, which include humans and leopards. 
• The long call is longer than any other animals call in the world.
• Monkeys have tails but orangs, like other great apes, do not. 
• Orangs walk on the sides of their feet not on the soles.  

Books & Periodicals

Anon, Alice.  Orangutan, Endangered Ape: New York, Atheneum, 1977.

Ashby, Ruth, The Orangutan. New York: Dillion Press, 1994. 

"Fading Away." Scholastic News. Edition 4; 2/7/2005, Vol. 67 Issue 14, p5-5, 1/3p, 2c.

Green, Carl R. The Orangutan.  Mankato, MN: Crestwood Publishing House, 1987.

Kaplan, Gisela; Rogers, Leslie J. The Orangutans. New York: Perseus Publishing, 2000.

Resnick, Joe, Orly The Orangutan. Flying Frog Publishing, 2001.

Woods, Mae, Orangutans. Edina, Abdo Consulting, 1998.

World Wide Web

"All About Orangutans."  Enchanted Learning.  07 December 2006 <http://www.enchantedlearning.com/subjects/apes/orangutan/index.shtml>.